A lawyer for Mustafa al-Hawsawi, a Saudi citizen held in the Guantanamo Bay US detention facility, has asked a Vilnius court to grant victim status to her client because he could have been kept in a secret CIA black-site prison near Vilnius.

According to Ingrida Botyrienė, al-Hawsawi's lawyer, suspicions that al-Hawsawi was kept in the alleged secret CIA black site in Lithuania are substantiated by a US Senate report and evidence collected by non-governmental organizations. Prosecutors call the evidence "assumptions and interpretations".

The 47-year-old Saudi man's request for victim status has been filed in a pre-trial investigation that was opened in Lithuania in February 2014 at numerous NGOs' request and was expanded in December of that year following the Senate report on the CIA's torture of suspected terrorists.

The Senate did not name any specific countries, but human rights watchdogs believe the "detention center Violet" named in the report was located in Antaviliai, not far from the Lithuanian capital. According to the report, the site was closed down in 2016 after the state refused to provide medical help to al-Hawsawi.

Botyrienė told BNS that the Saudi citizen had been denied victim status by Lithuanian prosecutors "based on very formal arguments that there is no evidence that the man suffered any harm in Lithuania".

According to the lawyer, US authorities have admitted that al-Hawsawi was included in the CIA's special detention and interrogation program and was a so-called "high-value detainee". The European Court of Human Rights has concluded that interrogation techniques used on these persons amounted to torture.

She said that victim status would allow al-Hawsawi's lawyers to request access to the case-file of the investigation.

The lawyer says in her request to the Vilnius District Court that al-Hawsawi may face a death sentence.

The US government says that al-Hawsawi was a member of Al-Qaeda and was involved in the September 11, 2001 terror attacks.

Botyrienė has also asked to expand the ongoing pre-trial investigation to include crimes against humanity.

Prosecutors say that the investigation continues into the potential unlawful transportation of persons across the state border and abuse of authority and that there is no factual evidence to suggest that al- Hawsawi was tortured in Lithuania.

"No factual evidence has been obtained in this pre-trial investigation and no factual circumstances have been established to suggest that Mustafa Ahmed Adam al-Hawsawi could have suffered any sort of non-material, material or physical harm as a result of the criminal acts currently under investigation," Rita Stundienė, spokeswoman for the Prosecutor General's Office, told BNS.

"Procedural decisions in a pre-trial investigation cannot be based on assumptions or interpretations," she said.

As part of the pre-trial investigation, requests for legal assistance have been sent to Poland and Romania, which have also been accused of allowing the CIA to operate secret prisons for terrorism suspects, Sundienė said.

The spokeswoman gave no further information, saying that a part of the case-file has been classified as a state secret or an official secret.

Detained in Pakistan in 2003, al-Hawsawi is the second person whose lawyers say that their client was detained in Lithuania. Lawyers acting for Abu Zubaydah, a Saudi-born Palestinian national, have begun proceedings in the European Court of Human Rights.

A Lithuanian parliamentary inquiry in late 2009 identified two sites, one in Vilnius and the other close to the Lithuanian capital, that could have been used as detention facilities.

The investigation also found that several CIA-related flights had landed in Vilnius and Palanga between 2003 and 2006, but it did not answer the question of whether any terror suspects had been actually brought to the country.